Reconfigurable optical networks

ABSTRACT

A system, e.g. a reconfigurable electro-optical network, includes input and output waveguides. The input waveguide is configured to receive a first input optical signal including a first modulated input wavelength channel. The output waveguide is configured to receive a carrier signal including an unmodulated output wavelength channel. An input microcavity resonator is configured to derive a modulated electrical control signal from the modulated input wavelength channel. A first output microcavity resonator is configured to modulate the output wavelength channel in response to the control signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.13/538,525 (the ′525 Application) filed on Jun. 29, 2012 andincorporated by reference herein. This application is further related toU.S. patent application Ser. No. 13/800,634 (the ′634 Application) filedon even date herewith and incorporated by reference herein. The presentapplication claims the benefit to the previously filed U.S. ProvisionalPatent Application No. 61/667,380 of the same title, filed Jul. 2, 2012,and which is incorporated herein by reference in its entirety. Thepresent application further claims the benefit to the previously filedU.S. Provisional Patent Application No. 61/667,374 also of the sametitle, filed Jul. 2, 2012 (the ′374 Application), and which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

This application is directed, in general, to optical communicationssystems and methods.

BACKGROUND

This section introduces aspects that may be helpful to facilitating abetter understanding of the inventions. Accordingly, the statements ofthis section are to be read in this light and are not to be understoodas admissions about what is in the prior art or what is not in the priorart.

Optical switching networks employ a switching topology that may bereferred to as an “optical switch fabric.” As the size and speed of suchnetworks grows, new optical switch fabrics that provide greatercapability are needed to keep pace with such growth. One aspect ofcapability to be addressed is configuration of such optical networks.

SUMMARY

One aspect provides a system, e.g. a reconfigurable electro-opticalnetwork, including first input and first output waveguides. The inputwaveguide is configured to receive a first input optical signal. Thesignal includes a first modulated input wavelength channel. The outputwaveguide is configured to receive a carrier signal including anunmodulated output wavelength channel. A first input microcavityresonator is configured to derive a modulated electrical control signalfrom the modulated input wavelength channel. A first output microcavityresonator is configured to modulate the output wavelength channel inresponse to the control signal.

Another aspect provides a method, e.g. for forming a reconfigurableelectro-optical network. The method includes forming a first inputwaveguide capable of receiving a first input optical signal, the signalincluding a first modulated input wavelength channel. A first outputwaveguide is formed that is capable of receiving a carrier signal, thecarrier signal including an unmodulated output wavelength channel. Afirst input microcavity resonator is formed that is configured to derivea modulated electrical control signal from the modulated inputwavelength channel. A first output microcavity resonator is formed thatis configured to modulate the output wavelength channel in response tothe control signal.

In some of the above embodiments the first input microcavity resonatormay be one of a plurality of input microcavity resonators configured toderive an electrical control signal from each one of a correspondingplurality of modulated input wavelength channels. The first outputmicrocavity resonator may be one of a plurality of output microcavityresonators each configured to modulate a corresponding output wavelengthchannel in response to a corresponding one of the control signals. Acontroller is configured to reconfigure connectivity between the inputmicrocavity resonators and the output microcavity resonators.

In any of the above embodiments the controller may include across-connect switch having N inputs and N outputs, and configured toprovide a plurality of unique combinations of signal paths of thecontrol signals between the input microcavity resonators and the outputmicrocavity resonators. In some such embodiments the cross-connectswitch has N outputs, and includes a plurality of sub-switches eachbeing configured to switch √N inputs to √N outputs. In some embodimentsthe cross-connect switch provides N! unique combinations of signalpaths.

In any of the above embodiments the input and output waveguides may belocated on a first substrate and the controller may be located on asecond substrate. In some such embodiments the first and secondsubstrates are may both be bonded to an interposed interconnectsubstrate.

In any of the above-described embodiments the microcavity resonators maycomprise ring resonators. In any of the above-described embodiments theinput wavelength channel and the output wavelength channel may eachemploy a same wavelength. In any of the above-described embodiments thesystem may include an optical source configured to produce the carriersignal. In such embodiments the optical source may be configured toproduce a plurality of wavelength components in the optical S, C, or Lbands.

Another embodiment is a system comprising an NM×NM electricalcross-connect, N first sets and N second sets. Of the N first sets, eachfirst set including M ring resonators optically coupled to an opticalwaveguide corresponding to the same first set, each ring resonator ofthe first sets having an optical-to-electrical output connected to acorresponding electrical input of the NM×NM electrical cross-connect. Ofthe N second sets, each second set includes M ring resonators opticallycoupled to an optical waveguide corresponding to the same second set,each ring resonator of the second sets having an optical-to-electricalinput connected to a corresponding output of the NM×NM electricalcross-connect.

Some such embodiments further comprise N optical transmitters capable oftransmitting on M optical transmission channels, each transmitteroptically coupled to a corresponding one of the optical waveguidesoptically coupled to one of the first sets. Some such embodimentsfurther comprise N optical receivers capable of receiving on M opticalreception channels, each receiver optically coupled to a correspondingone of the optical waveguides optically coupled to one of the secondsets. In any such embodiments, the electrical cross-connect may beconfigured to connect each ring resonator of a same one of the firstsets to a different one of the second sets. In any such embodiments, theelectrical cross-connect may be configured to connect each ringresonator of one of the first sets to a different one of the secondsets. In any such embodiments, the electrical cross-connect may beconfigured to connect each ring resonator of one of the second sets to adifferent one of the first sets. In any such embodiments, the electricalcross-connect is configured to connect each ring resonator of one of thesecond sets to a different one of the first sets. In any suchembodiments, the NM×NM electrical cross-connect may be dynamicallyreconfigurable.

BRIEF DESCRIPTION

Reference is now made to the following descriptions taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 illustrates a system, e.g. a reconfigurable electro-opticalswitching matrix, according to one embodiment in which electrical datasignals produced from data-modulated optical carriers are routed by areconfigurable electrical switch to a plurality of output microcavityresonators (e.g. ring resonators) to data-modulate wavelength channelsof output optical signals;

FIG. 1A is a block diagram illustrating how the system of FIG. 1 may beused to implement an optical communication system between N electronicdevices that transmit data-modulated optical carriers and N electronicdevices, which receive data-modulated optical carriers;

FIG. 2 schematically illustrates aspects of a wavelength comb includinga number of wavelength channels of a WDM optical signal;

FIG. 3 illustrates an optical-to-electric converter used in variousembodiments to convert an optical signal, e.g. a binary phase-shiftkeyed (BPSK) optical signal, to a corresponding electrical signal;

FIG. 4 illustrates a detail view of the system of FIG. 1 for signalconversion and routing of one received WDM optical signal to an inputsub-switch of the reconfigurable electrical switch;

FIG. 5 illustrates a detail view of the system of FIG. 1 for signalrouting and conversion from one output of the reconfigurable electricalswitch of FIG. 1 to microcavity resonators configured to modulate outputoptical wavelength channels;

FIGS. 6A-6C illustrate cross-sectional views of planar structures thatmay be used to produce various embodiments of components of the systemof FIG. 1;

FIG. 7 presents a flow diagram of a method, e.g. for forming a systemaccording to various embodiments, e.g. the system of FIG. 1; and

FIG. 8 presents a flow diagram of a method, e.g. for forming a systemaccording to various embodiments, e.g. the system of FIG. 1.

DETAILED DESCRIPTION

The inventors have determined that a compact and flexible architecturefor switching data between optical WDM (wavelength-division multiplexed)channels in an optical network may be implemented using microcavityresonators coupled to input waveguides to convert receiveddata-modulated optical signal streams to corresponding data-modulatedelectrical signal streams, and electrically switching the data-modulatedelectrical signal streams to a plurality of microcavity resonators,which re-convert the individual data-modulated electrical signals intooutput data-modulated optical carriers.

Some structures and/or methods described in the '374 Application and/orthe '249 Application may be suitable for making or using similarstructures and/or methods of the present application.

FIG. 1 presents a system 100, e.g. an embodiment of an M×Nreconfigurable optical network 100 in one nonlimiting example. Theparameter M describes a number of wavelength channels in a wavelengthdivision multiplexed (WDM) optical signal that may be received by thesystem 100 on each of N WDM modulated optical signals. The system 100 isillustrated without limitation with M=N=6. Those skilled in thepertinent art will appreciate that the principles of the disclosedembodiments are adaptable to different values of M and N, and that M andN need not be equal.

The system 100 includes three sections that are described in turn, areceiver stage 105 that which performs optical-to-electrical conversion,an electrical switching stage 110, and a transmitter stage 115 thatperforms electrical-to-optical conversion.

The receiver stage 105 includes a plurality of input waveguides 120-1 .. . 120-6, collectively referred to as input waveguides 120. Eachwaveguide 120-1 . . . 120-6 may receive a WDM optical signal 122-1 . . .122-6, including as many as M (e.g. 6) data-modulated wavelengthchannels.

Each of the multi-channel optical signals 122 may be coupled to thesystem 100 via, e.g. grating couplers. As appreciated by those skilledin the optical arts, a WDM signal may be schematically described by afrequency or wavelength comb. FIG. 2 illustrates a representativewavelength comb 200 that includes six wavelength channels λ₁ . . . λ₆.The wavelength channel components of the comb 200 may be spaced by a WDMgrid spacing Δλ, e.g. a regular, about even spacing of the wavelengthcomponents by a same frequency difference, e.g. about 100 GHz.

The receiver stage 105 further includes a plurality of input microcavityresonator sets 125-1 . . . 125-N (e.g. N=6), each including Mmicrocavity resonators 130 (e.g. M=6). Each microcavity resonator 130may be, e.g. a ring resonator (microring) or a disk resonator(microdisk) configured to couple to a particular wavelength channel ofan optical signal 122 propagating in an adjacent waveguide 120. Theresonant wavelength is not limited to any particular value, and may beselected to be in any wavelength band used in optical communications,e.g. in the S band (1460 nm-1530 nm), the C band (1530 nm-1565 nm) orthe L band (1565 nm-1625 nm), e.g., by adjusting the refractive index ofthe individual microcavity resonator.

In the remaining discussion, the microcavity resonators 130 aredescribed as ring resonators without limitation thereto. The microcavityresonator sets 125 may therefore also be referred to as ring resonatorssets 125. An individual ring resonator may be designated “130-MN”, wherethe integers M and N are replaced by that resonator's assignment to aparticular one of the M wavelength channels and a particular one of theN received input signals. Moreover, an optical signal may be describedby its frequency or equivalently by its wavelength λ_(M). Each ringresonator set 125 is optically coupled to a corresponding one of theinput waveguides 120.

An individual one of the ring resonators 130 in each set 125 isconfigured to couple to a corresponding one of the wavelength channelsof the received multi-channel optical signal. Each ring resonator 130has a resonant wavelength, which is determined in part by its opticalpath length and is the wavelength at which optical power couplesresonantly from the associated input waveguide 120 to that ringresonator 130. In some or all of the ring resonators 130 adjustment ofthe resonant wavelength may be performed, e.g. by a heater, which canadjust the effective refractive index of a corresponding one of the ringresonators 130. Thus, e.g., the ring resonators 130-11, 130-12 . . .130-16 are configured to couple to the λ₁ wavelength channel, the ringresonators 130-21, 130-22 . . . 130-26 are configured to couple to theλ₂ wavelength channel, etc.

An optical-to-electrical (OE) converter 300 is located adjacent eachring resonator 130. One such OE converter 300 is illustrated in FIG. 3.The OE converter 300 includes a waveguide segment 310 and a photodiode320. The photodiode 320 converts optical power propagating within thewaveguide segment 310 to an electrical signal. When a particularwavelength channel couples to a particular ring resonator 130, theoptical power within the ring is also coupled to the associatedwaveguide segment 310. Thus the OE converter 300 transfers the receivedoptical signal to the electrical domain. Collectively, the M×N instancesof the OE converter 300 may produce up to M×N data-modulated electricalsignals 138 (FIG. 1) from the received M×N separate data-modulatedoptical carriers, i.e., 36 in the present example embodiment.

Returning to FIG. 1, the electrical switching stage 110 includes an M×Nby M×N electrical cross-connect switch 140 (e.g., a NM×NM electricalcross-connect) that receives the M×N electrical signals at its inputsand routes each signal to a single corresponding one of its M×N outputsunder control of a controller 145. In particular, the electricalcross-connect switch 140 is configured to direct one of the convertedelectrical signal streams from each OE converter set 125-1 to 125-N toeach of the electrical-to-optical (EO) converter sets 175-1 to 175-M.The mapping of the data-modulated electrical signal streams 138 from theinputs to the outputs of the switch 140 may be selectively changed bythe operation of the controller 145 is discussed further below.

The implementation of the switch 140 is not limited to any particularform. In the illustrated example embodiment, the switch 140 is “square”,meaning the number of inputs is equal to the number of outputs, and thenumber is a squared integer, e.g. M×N=36, where M=N=6. In suchembodiments, the switch 140 may be efficiently implemented using about√N input sub-switches 150-1 . . . 150-6, about √N output sub-switches155-1 . . . 155-6, and about √N intermediate sub-switches 160-1 . . .160-6. Alternatively and without limitation, the switch 140 may beimplemented directly as an N²×N² (e.g. 36×36) switch. In someembodiments M≠N, such as when the number of wavelength channels of thereceived optical signals 122 is not equal to the number of opticalsignals 122 received.

FIG. 4 illustrates more specifically the connections between onemicrocavity resonator set, e.g. the set 125-1, and the inputs of asub-switch 150, e.g. the sub-switch 150-1. The output of each OEconverter 300, e.g. one of the electrical signals 138, is connected viaan individual electrical path to a corresponding input of the sub-switch150-1. The illustrated embodiment is but one possible interconnectionbetween the OE converters 300 and the sub-switch 150-1. Because theswitch 140 may arbitrarily map inputs to outputs, the signals 138 may bepresented in any order to the switch 140.

Referring again to FIG. 1, the transmitter stage 115 includes an opticalsource 162 and M optical waveguides 165, e.g. M=6. The optical source162 produces M continuous wave (CW) optical signals 170-1 to 170-Mhaving N wavelength component channels, e.g. as illustrated by theunmodulated frequency comb such as described in FIG. 2. The opticalsource 162 may include various components, e.g. multi-wavelength-channellaser sources and optical power splitters. The wavelength componentchannels may have the same wavelengths as those of the received opticalsignals 122, but are not limited thereto. The waveguides 165 receive theoptical signals 170 having N wavelength channels, e.g. N=6.

A corresponding microcavity resonator set 175-1 to 175-M is opticallycoupled to and located adjacent to a segment of a corresponding one ofthe waveguides 165 and includes N microcavity resonators 180. Theresonators 180 may also be designated by M and N, e.g. 180-MN. Eachmicrocavity resonator 180 within each set 175 is configured to couple toone of the wavelength channels of the CW signal 170 propagating withinthat waveguide 165. Thus, for the illustrated example, one microcavityresonator 180 in each set 175 may be configured to have a resonantfrequency at each of about λ₁, λ₂, λ₃, λ₄, λ₅, and λ₆. Some or all ofthe microcavity resonators may include a tuning heater that sets theresonant optical wavelength therein.

The resonant optical wavelength of each ring resonator 180 is alsomodulated by one of M×N electrical data-modulated electrical signalstreams 142 from the cross-connect switch 140. A subset of N of thedata-modulated signal streams 138 from one the sub-switch 155 controls acorresponding one of each of the resonator sets 175, the correspondingones being configured to couple to a single one of the wavelengthchannels. For example, the sub-switch 155-1 provides N signals (e.g. N=6in FIG. 1), each signal being configured to control the ring resonator180 in each set 175 that is configured to modulate λ₁. From anotherviewpoint, a subset of M of the data-modulated signal streams 142 fromthe switch 140 controls the ring resonators in a corresponding set 175,the set 175 including M ring resonators 180 corresponding to λ₁, λ₂, . .. λ_(M), e.g. M=6. The remaining signals 142 from the switch 140 areconfigured analogously to modulate the remaining wavelength channels inthe optical waveguides 165-1 to 165-M.

FIG. 5 illustrates more specifically the connections between asub-switch 155, e.g. the sub-switch 155-1, and a row of the ringresonators 180, e.g. those corresponding to the λ₁ wavelength channels.The respective outputs of the sub-switch 155-1 are each routed to asingle one of the ring resonators 180. However, as before the switch 140may arbitrarily map the inputs to outputs, so the wavelength channeldata may be connected in any order to the ring resonators 180.

Referring again to FIG. 1, modulation of the ring resonators 180 may beby, e.g. electro-optic, thermal or free-carrier modulation of theoptical patch length. The modulation data-modulates the coupledwavelength channel of the carrier signal propagating in thecorresponding waveguide 165. Additional aspects of such modulation aredescribed in the '525 Application. By modulating the resonantfrequencies of each of the ring resonators 180, the system 100 producesoutput optical signal streams 185. The system 100 may thereby transferthe data received on each one of the wavelength channels of the inputsignals 122 to a selected corresponding one wavelength channel of acorresponding one of the output signals 185.

Thus the system 100 is expected to provide a high-speed and flexiblearchitecture for configuring an optical switch fabric of an opticalcommunication system. The system 100 may be used in many types ofoptical systems. In one example, the system may be used to route opticalsignals within an integrated photonic optical processor. In anotherexample, the system 100 may provide quasi-static or dynamicreconfiguration of optical paths in a communication system, e.g. along-haul optical communication system. The system 100 may also be usedto enable machine-to-machine optical communications in a data center.

FIG. 1A illustrates how the system 100 enables machine-to-machinecommunications between a set of N machines 900-1 to 900-N, which outputoptical data-modulated carriers, and a set of N machines 1000-1 to1000-N, which receive and process data-modulated optical carriers. Eachmachine 900-1 to 900-N connects via a corresponding optical fiber 120-1to 120-N to a corresponding microcavity resonator set 125-1 to 125-N.Each machine 1000-1 to 1000-N connects via a corresponding optical fiber165-1 to 165-N to a corresponding microcavity resonator set 175-1 to175-N.

In the system 100, each machine 900-1 to 900-N has an opticaltransmitter capable of outputting data-modulated optical carriers in Mwavelength channels.

In the system 100, each machine 1000-1 to 1000-M has an optical receivercapable of inputting and processing data-modulated optical carriers in Mwavelength channels.

In one embodiment, the system 100 is a data center with N digital dataprocessors 900-1 to 900-N and N digital data storage devices 1000-1 to1000-N. In other embodiments, the devices 900-1 to 900-N may bedifferent types of devices capable transmitting data-modulated opticalcarriers in M wavelength channels. In other embodiments, the devices1000-1 to 1000-N may be different types of devices capable receiving andprocessing data-modulated optical carriers in M wavelength channels. Thewavelengths of the M wavelength channels of the machines 900-1 to 900-Nmay be, but need not be, the same as the M wavelength channels of themachines 1000-1 to 1000-N.

In some such embodiments, the system 100 enables each of the N digitaldata processors to communicate a separate digital data stream to any ofthe digital data storage devices 1000-1 to 1000-N.

The optical components of the system 100 may be formed conventionally,e.g. as planar structures formed over a silicon substrate, e.g. asilicon wafer. A convenient platform on which to form the system 100 isa silicon-on-insulator (SOI) wafer, but embodiments of the invention arenot limited thereto. For example, a dielectric layer, e.g. plasma oxide,could be formed on any suitable substrate, and a silicon layer could beformed thereover by any suitable method. Other embodiments may use asubstrate formed from, e.g. glass, sapphire or a compound semiconductor.Those skilled in the pertinent art are familiar with such fabricationtechniques.

In some embodiments optical and electrical components of the system 100are formed on a same substrate. In such a system, e.g. silicon-basedelectronic components may be formed on one region of a photonicintegrated circuit (PIC), and optical components may be formed onanother region of the PIC. Interconnects may provide conductive pathsfrom the domain converters 300 to the electrical switching stage 110.

In other embodiments, such as represented by FIG. 6A, portions of anopto-electronic system may be formed on separate substrates. FIG. 6Aillustrates a system 600, formed according to one embodiment. Electricalcomponents are formed on an electrically active substrate 610, opticalcomponents are formed on an optical substrate 620, and interconnects areformed on an interconnect substrate 630. The substrates 610, 620 and 630are then joined to form the operable system 600.

The electronic substrate 610 may include electronic components, e.g.transistors, diodes, resistors and capacitors, needed to implementelectrical functions of the system 100. Such functions include, but arenot limited to, the switch 140 and the controller 145, includingswitching, signal conditioning and amplification. The electronicsubstrate 610 may include a base layer 640, e.g. a silicon wafer, and anactive layer 650 that includes electronic devices and interconnects. Thesubstrate 610 may be formed from any conventional and/orfuture-discovered processes, and is not limited to any particularmaterial types. By way of example, without limitation, such materialsmay include silica, SiN, silicon, InP, GaAs, and copper or aluminuminterconnects.

The optical substrate 620 includes various optical components of thesystem 100, e.g. waveguides, microcavity resonators, power splitters,power combiners, and photodiodes. The optical components may be formedfrom planar or ridge structures by conventional and/or novel processes.Such components typically include a core region and a cladding region.The core regions may be formed from any conventional or nonconventionaloptical material system, e.g. silicon, LiNbO₃, a compound semiconductorsuch as GaAs or InP, or an electro-optic polymer. Some embodimentsdescribed herein are implemented in Si as a nonlimiting example. Whileembodiments within the scope of the invention are not limited to Si,this material provides some benefits relative to other material systems,e.g. relatively low cost and well-developed manufacturinginfrastructure. The cladding region may include homogenous orheterogeneous dielectric materials, e.g. silica or benzocyclobutene(BCB). Some portions of the cladding region may include air, which forthe purposes of this discussion includes vacuum.

The interconnect substrate 630 includes additional interconnectstructures that may configure operation of the system 600. Theinterconnect substrate 630 may include any dielectric and conductive(e.g. metallic) materials needed to implement the desired connectivity.In some cases, formation of the substrate 630 may include the use of ahandle wafer to provide mechanical support, after which the substrate630 is removed from the handle.

The electronic substrate 610 may be joined to the interconnect substrate630 by, e.g. a bump process or, as illustrated, a wafer bonding process.Such processes are well known to those skilled in, e.g. semiconductormanufacturing, and may include chemical mechanical polishing (CMP) toprepare the substrate surfaces for bonding. The interconnect substrate630 may be joined to the optical substrate 620 by, e.g. a bump processas illustrated in FIG. 6A, or a wafer bonding process as illustrated inFIG. 6B. In the bump process, solder balls 660 join interconnectstructures in the substrate 630 to via structures 670 in the opticalsubstrate 620. The via structures 670 may provide electrical and/ormechanical connectivity between substrates 620 and 630.

FIG. 6C illustrates another embodiment of the system 600 in which theinterconnections and optical functions are combined into an integratedsubstrate 680. In the illustrated embodiment the substrate 680 includesthe optical substrate 620 and interconnect layers 630 a and 630 b formedon either side of the substrate 620. The integrated substrate 680 maythen be joined to the electrical substrate 610 by, e.g. wafer bonding.

The separate formation of the electronic substrate 610, the interconnectsubstrate 630 and the optical substrate 620 may serve at least one ofseveral purposes. First, the thermal budget required to form somefeatures, e.g. high quality waveguides in the optical substrate 620, maybe incompatible with other features, such as doping profiles oftransistors in the substrate 610. Second, the substrates 610, 620 and630 may be formed separately by entities with specialized skills and/orfabrication facilities and joined by another entity. Third, wheresecurity is desired regarding the function of the assembled system 600,the fabrication operations may be assigned to the various entities suchthat no one entity acquires sufficient knowledge to determine thefunctionality of the device. The final assembly may then be completedunder secure conditions to provide confidentiality of the operation ofthe assembled system 600.

Turning to FIG. 7, a method 700 is presented, e.g. for forming thesystem 100 according to various embodiments. The steps of the method 700are described without limitation by reference to elements previouslydescribed herein, e.g. in FIGS. 1-6. The steps of the method 700 may beperformed in another order than the illustrated order, and in someembodiments may be omitted altogether and/or performed concurrently orin parallel groups. This method 700 is illustrated without limitationwith the steps thereof being performed in parallel fashion, such as byconcurrent processing on a common substrate. Other embodiments, e.g.those utilizing multiple substrates, may perform the steps partially orcompletely sequentially and in any order.

The method 700 begins with an entry 710. In a step 720, a first inputwaveguide, e.g. the input waveguide 120-1, is formed. This waveguide isconfigured to receive a first input optical signal including a firstmodulated input wavelength channel. In a step 730, a first outputwaveguide, e.g. the waveguide 165-1, is formed. This waveguide isconfigured to receive a carrier signal including an unmodulated outputwavelength channel. In a step 740 a first input microcavity resonator,e.g. the ring resonator 130-11, is formed. The ring resonator isconfigured to derive a modulated electrical control signal from themodulated input wavelength channel, e.g. by transferring optical powerto the domain converter 300. In a step 750, a first output microcavityresonator is formed, e.g. the ring resonator 180-11. This microcavityresonator is configured to modulate said output wavelength channel inresponse to said control signal.

FIG. 8 presents another method 800, e.g. for forming the system 100. Thesteps of the method 800 are described without limitation by reference toelements previously described herein, e.g. in FIGS. 1-6. The steps ofthe method 800 may be performed in another order than the illustratedorder, and in some embodiments may be omitted altogether and/orperformed in parallel or in parallel groups. Herein and in the claims,“provided” or “providing” means that a device, substrate, structuralelement, etc., may be manufactured by the individual or business entityperforming the disclosed method, or obtained thereby from a source otherthan the individual or entity, including another individual or businessentity.

The method includes a step 810, in which a first substrate is provided,e.g. the substrate 620. The substrate includes an input waveguide, e.g.the waveguide 120-1, and an output waveguide, e.g. the waveguide 165-1.An input microcavity resonator, e.g. the resonator 130-11, is configuredto derive a modulated electrical control signal from a modulated inputwavelength channel propagating within the input waveguide. An outputmicrocavity resonator, e.g. the resonator 175-11, is configured tomodulate an output wavelength channel propagating within the outputwaveguide in response to the control signal.

In a step 820 a second substrate is provided, e.g. the substrate 610.The second substrate includes a control stage formed thereover, e.g. theelectrical switching stage 110. The control stage is configured to routethe electrical control signal from the input microcavity resonator tothe output microcavity resonator.

In a step 830 the first and second substrates are joined, therebyconnecting the control stage to the microcavity resonators.

In some embodiments of the method 800 joining the first and secondsubstrates includes joining both substrates to a third substrate thatincludes conductive interconnections that connect the controller to theoutput microcavity resonator.

Those skilled in the art to which this application relates willappreciate that other and further additions, deletions, substitutionsand modifications may be made to the described embodiments.

What is claimed is:
 1. A system, comprising a first input waveguidelocated on a first substrate and configured to receive a first inputoptical signal including a plurality of modulated input wavelengthchannels; a first output waveguide located on said first substrate andconfigured to receive a carrier signal including a plurality ofunmodulated output wavelength channels; a plurality of input microcavityresonators each configured to derive a corresponding modulatedelectrical control signal from a corresponding one of said modulatedinput wavelength channels; a plurality of output microcavity resonatorseach configured to modulate a corresponding one of said outputwavelength channels in response to said control signal; and a controllerlocated on a second substrate and configured to reconfigure connectivitybetween said input microcavity resonators and said output microcavityresonators.
 2. The system of claim 1, wherein said controller includes across-connect switch configured to provide a plurality of uniquecombinations of paths of said control signals between said inputmicrocavity resonators and said output microcavity resonators.
 3. Thesystem of claim 2, wherein said cross-connect switch has N inputs and Noutputs, and includes a plurality of sub-switches each being configuredto switch √{square root over (N)} inputs to √{square root over (N)}outputs.
 4. The system of claim 1, wherein said first and secondsubstrates are both bonded to an interposed interconnect substrate. 5.The system of claim 1, wherein said microcavity resonators comprise ringresonators.
 6. The system of claim 1, wherein one of said inputwavelength channels employs the same wavelength as one of said outputwavelength channels.
 7. The system of claim 1, further comprising anoptical source configured to produce said carrier signal.
 8. The systemof claim 7, wherein said optical source is configured to produce aplurality of wavelength components in the optical S, C, or L bands.
 9. Amethod, comprising forming a first input waveguide located on a firstsubstrate and capable of receiving a first input optical signalincluding a plurality of modulated input wavelength channels; forming afirst output waveguide located on said first substrate and capable ofreceiving a carrier signal including a plurality of unmodulated outputwavelength channels; forming a plurality of input microcavity resonatorseach configured to derive a corresponding modulated electrical controlsignal from a corresponding one of said modulated input wavelengthchannels; forming a plurality of output microcavity resonators eachconfigured to modulate a corresponding one of said output wavelengthchannels in response to said control signal; and forming a controllerlocated on a second substrate and configured to reconfigure connectivitybetween said input microcavity resonators and said output microcavityresonators.
 10. The method of claim 9, wherein said controller includesa cross-connect switch configured to provide a plurality of combinationsof paths of said control signals between said input microcavityresonators and said output microcavity resonators.
 11. The method ofclaim 10, wherein said cross-connect switch has N inputs and N outputs,and includes a plurality of sub-switches each being configured to switch√{square root over (N)} inputs to √{square root over (N)} outputs. 12.The method of claim 9, further comprising connecting said first andsecond substrates via an interposing interconnect substrate.
 13. Themethod of claim 9, wherein said microcavity resonators comprise ringresonators.
 14. The method of claim 9, wherein one of said inputwavelength channels employs the same wavelength as channel and one ofsaid output wavelength channels channel each employ a same wavelength.15. The method of claim 9, further comprising configuring an opticalsource to produce said carrier signal.
 16. The method of claim 15,wherein said optical source is configured to produce a plurality ofwavelength components in the optical S, C, or L bands.